A 30-year-old woman has been seriously injured in a collision with a car this morning in Kidlington.
It happened at about 7.55am on the A4260 Oxford Road, which is now partially closed at the junction with Bicester Road while emergency services are at the scene.
South Central Ambulance Service spokesman David Gallagher said the woman had been taken to the John Radcliffe Hospital, in Oxford.
He added: "We sent an ambulance, an officer and the air ambulance rapid response car to the scene.
"The pedestrian had sustained serious head and pelvic injuries."
Drivers in the area are facing delays and Stagecoach says its services are temporarily unable to serve the road.
Ben Hart, of Blenheim Road, said he was passing on the way to the shops at about 7.55am when he saw people gathered around the woman.
He said: "I think she had been involved in an accident while she was on her bike.
"There was about five people gathered around her and a car parked further on.
"I carried on going but about half an hour later there was five police cars and two ambulances there."
Mr Hart said he saw the woman being taken away by paramedics on a stretcher at about 9am.
Oxford-bound traffic was being diverted via Bicester Road, he added.
SERVICE UPDATE: Due to a road closure in Kidlington all services will be unable to serve Oxford road, Kidlington at this time.
— Stagecoach Oxford (@Stagecoach_Ox) March 17, 2017